//
//  ========================================================================
//  Copyright (c) 1995-2017 Mort Bay Consulting Pty. Ltd.
//  ------------------------------------------------------------------------
//  All rights reserved. This program and the accompanying materials
//  are made available under the terms of the Eclipse Public License v1.0
//  and Apache License v2.0 which accompanies this distribution.
//
//      The Eclipse Public License is available at
//      http://www.eclipse.org/legal/epl-v10.html
//
//      The Apache License v2.0 is available at
//      http://www.opensource.org/licenses/apache2.0.php
//
//  You may elect to redistribute this code under either of these licenses.
//  ========================================================================
//

package org.eclipse.jetty.http;

import java.nio.ByteBuffer;
import java.nio.charset.StandardCharsets;
import java.util.Arrays;
import java.util.EnumSet;
import java.util.List;
import java.util.Locale;

import org.eclipse.jetty.http.HttpTokens.EndOfContent;
import org.eclipse.jetty.util.ArrayTernaryTrie;
import org.eclipse.jetty.util.ArrayTrie;
import org.eclipse.jetty.util.BufferUtil;
import org.eclipse.jetty.util.Trie;
import org.eclipse.jetty.util.TypeUtil;
import org.eclipse.jetty.util.Utf8StringBuilder;
import org.eclipse.jetty.util.log.Log;
import org.eclipse.jetty.util.log.Logger;

import static org.eclipse.jetty.http.HttpCompliance.LEGACY;
import static org.eclipse.jetty.http.HttpCompliance.RFC2616;
import static org.eclipse.jetty.http.HttpCompliance.RFC7230;
import static org.eclipse.jetty.http.HttpTokens.CARRIAGE_RETURN;
import static org.eclipse.jetty.http.HttpTokens.LINE_FEED;
import static org.eclipse.jetty.http.HttpTokens.SPACE;
import static org.eclipse.jetty.http.HttpTokens.TAB;


/* ------------------------------------------------------------ */
/** A Parser for 1.0 and 1.1 as defined by RFC7230
 * <p>
 * This parser parses HTTP client and server messages from buffers
 * passed in the {@link #parseNext(ByteBuffer)} method.  The parsed
 * elements of the HTTP message are passed as event calls to the
 * {@link HttpHandler} instance the parser is constructed with.
 * If the passed handler is a {@link RequestHandler} then server side
 * parsing is performed and if it is a {@link ResponseHandler}, then
 * client side parsing is done.
 * </p>
 * <p>
 * The contract of the {@link HttpHandler} API is that if a call returns
 * true then the call to {@link #parseNext(ByteBuffer)} will return as
 * soon as possible also with a true response.  Typically this indicates
 * that the parsing has reached a stage where the caller should process
 * the events accumulated by the handler.    It is the preferred calling
 * style that handling such as calling a servlet to process a request,
 * should be done after a true return from {@link #parseNext(ByteBuffer)}
 * rather than from within the scope of a call like
 * {@link RequestHandler#messageComplete()}
 * </p>
 * <p>
 * For performance, the parse is heavily dependent on the
 * {@link Trie#getBest(ByteBuffer, int, int)} method to look ahead in a
 * single pass for both the structure ( : and CRLF ) and semantic (which
 * header and value) of a header.  Specifically the static {@link HttpHeader#CACHE}
 * is used to lookup common combinations of headers and values
 * (eg. "Connection: close"), or just header names (eg. "Connection:" ).
 * For headers who's value is not known statically (eg. Host, COOKIE) then a
 * per parser dynamic Trie of {@link HttpFields} from previous parsed messages
 * is used to help the parsing of subsequent messages.
 * </p>
 * <p>
 * The parser can work in varying compliance modes:
 * <dl>
 * <dt>RFC7230</dt><dd>(default) Compliance with RFC7230</dd>
 * <dt>RFC2616</dt><dd>Wrapped headers and HTTP/0.9 supported</dd>
 * <dt>LEGACY</dt><dd>Adherence to Servlet Specification requirement for
 * exact case of header names, bypassing the header caches, which are case insensitive,
 * otherwise equivalent to RFC2616</dd>
 * </dl>
 * @see <a href="http://tools.ietf.org/html/rfc7230">RFC 7230</a>
 */
public class HttpParser
{
    public static final Logger LOG = Log.getLogger(HttpParser.class);
    public final static int INITIAL_URI_LENGTH=256;

    /**
     * Cache of common {@link HttpField}s including: <UL>
     * <LI>Common static combinations such as:<UL>
     *   <li>Connection: close
     *   <li>Accept-Encoding: gzip
     *   <li>Content-Length: 0
     * </ul>
     * <li>Combinations of Content-Type header for common mime types by common charsets
     * <li>Most common headers with null values so that a lookup will at least
     * determine the header name even if the name:value combination is not cached
     * </ul>
     */
    public final static Trie<HttpField> CACHE = new ArrayTrie<>(2048);

    // States
    public enum FieldState
    {
        FIELD,
        IN_NAME,
        VALUE,
        IN_VALUE,
    }
    
    // States
    public enum State
    {
        START,
        METHOD,
        RESPONSE_VERSION,
        SPACE1,
        STATUS,
        URI,
        SPACE2,
        REQUEST_VERSION,
        REASON,
        PROXY,
        HEADER,
        CONTENT,
        EOF_CONTENT,
        CHUNKED_CONTENT,
        CHUNK_SIZE,
        CHUNK_PARAMS,
        CHUNK,
        TRAILER,
        END,
        CLOSE,  // The associated stream/endpoint should be closed
        CLOSED  // The associated stream/endpoint is at EOF
    }

    private final static EnumSet<State> __idleStates = EnumSet.of(State.START,State.END,State.CLOSE,State.CLOSED);
    private final static EnumSet<State> __completeStates = EnumSet.of(State.END,State.CLOSE,State.CLOSED);

    private final boolean DEBUG=LOG.isDebugEnabled(); // Cache debug to help branch prediction
    private final HttpHandler _handler;
    private final RequestHandler _requestHandler;
    private final ResponseHandler _responseHandler;
    private final ComplianceHandler _complianceHandler;
    private final int _maxHeaderBytes;
    private final HttpCompliance _compliance;
    private HttpField _field;
    private HttpHeader _header;
    private String _headerString;
    private String _valueString;
    private int _responseStatus;
    private int _headerBytes;
    private boolean _host;
    private boolean _headerComplete;

    /* ------------------------------------------------------------------------------- */
    private volatile State _state=State.START;
    private volatile FieldState _fieldState=FieldState.FIELD;
    private volatile boolean _eof;
    private HttpMethod _method;
    private String _methodString;
    private HttpVersion _version;
    private Utf8StringBuilder _uri=new Utf8StringBuilder(INITIAL_URI_LENGTH); // Tune?
    private EndOfContent _endOfContent;
    private long _contentLength = -1;
    private long _contentPosition;
    private int _chunkLength;
    private int _chunkPosition;
    private boolean _headResponse;
    private boolean _cr;
    private ByteBuffer _contentChunk;
    private Trie<HttpField> _fieldCache;

    private int _length;
    private final StringBuilder _string=new StringBuilder();

    static
    {
        CACHE.put(new HttpField(HttpHeader.CONNECTION,HttpHeaderValue.CLOSE));
        CACHE.put(new HttpField(HttpHeader.CONNECTION,HttpHeaderValue.KEEP_ALIVE));
        CACHE.put(new HttpField(HttpHeader.CONNECTION,HttpHeaderValue.UPGRADE));
        CACHE.put(new HttpField(HttpHeader.ACCEPT_ENCODING,"gzip"));
        CACHE.put(new HttpField(HttpHeader.ACCEPT_ENCODING,"gzip, deflate"));
        CACHE.put(new HttpField(HttpHeader.ACCEPT_ENCODING,"gzip,deflate,sdch"));
        CACHE.put(new HttpField(HttpHeader.ACCEPT_LANGUAGE,"en-US,en;q=0.5"));
        CACHE.put(new HttpField(HttpHeader.ACCEPT_LANGUAGE,"en-GB,en-US;q=0.8,en;q=0.6"));
        CACHE.put(new HttpField(HttpHeader.ACCEPT_CHARSET,"ISO-8859-1,utf-8;q=0.7,*;q=0.3"));
        CACHE.put(new HttpField(HttpHeader.ACCEPT,"*/*"));
        CACHE.put(new HttpField(HttpHeader.ACCEPT,"image/png,image/*;q=0.8,*/*;q=0.5"));
        CACHE.put(new HttpField(HttpHeader.ACCEPT,"text/html,application/xhtml+xml,application/xml;q=0.9,*/*;q=0.8"));
        CACHE.put(new HttpField(HttpHeader.PRAGMA,"no-cache"));
        CACHE.put(new HttpField(HttpHeader.CACHE_CONTROL,"private, no-cache, no-cache=Set-Cookie, proxy-revalidate"));
        CACHE.put(new HttpField(HttpHeader.CACHE_CONTROL,"no-cache"));
        CACHE.put(new HttpField(HttpHeader.CONTENT_LENGTH,"0"));
        CACHE.put(new HttpField(HttpHeader.CONTENT_ENCODING,"gzip"));
        CACHE.put(new HttpField(HttpHeader.CONTENT_ENCODING,"deflate"));
        CACHE.put(new HttpField(HttpHeader.TRANSFER_ENCODING,"chunked"));
        CACHE.put(new HttpField(HttpHeader.EXPIRES,"Fri, 01 Jan 1990 00:00:00 GMT"));

        // Add common Content types as fields
        for (String type : new String[]{"text/plain","text/html","text/xml","text/json","application/json","application/x-www-form-urlencoded"})
        {
            HttpField field=new PreEncodedHttpField(HttpHeader.CONTENT_TYPE,type);
            CACHE.put(field);

            for (String charset : new String[]{"utf-8","iso-8859-1"})
            {
                CACHE.put(new PreEncodedHttpField(HttpHeader.CONTENT_TYPE,type+";charset="+charset));
                CACHE.put(new PreEncodedHttpField(HttpHeader.CONTENT_TYPE,type+"; charset="+charset));
                CACHE.put(new PreEncodedHttpField(HttpHeader.CONTENT_TYPE,type+";charset="+charset.toUpperCase(Locale.ENGLISH)));
                CACHE.put(new PreEncodedHttpField(HttpHeader.CONTENT_TYPE,type+"; charset="+charset.toUpperCase(Locale.ENGLISH)));
            }
        }

        // Add headers with null values so HttpParser can avoid looking up name again for unknown values
        for (HttpHeader h:HttpHeader.values())
            if (!CACHE.put(new HttpField(h,(String)null)))
                throw new IllegalStateException("CACHE FULL");
        // Add some more common headers
        CACHE.put(new HttpField(HttpHeader.REFERER,(String)null));
        CACHE.put(new HttpField(HttpHeader.IF_MODIFIED_SINCE,(String)null));
        CACHE.put(new HttpField(HttpHeader.IF_NONE_MATCH,(String)null));
        CACHE.put(new HttpField(HttpHeader.AUTHORIZATION,(String)null));
        CACHE.put(new HttpField(HttpHeader.COOKIE,(String)null));
    }

    private static HttpCompliance compliance()
    {
        return HttpCompliance.RFC7230;
    }

    /* ------------------------------------------------------------------------------- */
    public HttpParser(RequestHandler handler)
    {
        this(handler,-1,compliance());
    }

    /* ------------------------------------------------------------------------------- */
    public HttpParser(ResponseHandler handler)
    {
        this(handler,-1,compliance());
    }

    /* ------------------------------------------------------------------------------- */
    public HttpParser(RequestHandler handler,int maxHeaderBytes)
    {
        this(handler,maxHeaderBytes,compliance());
    }

    /* ------------------------------------------------------------------------------- */
    public HttpParser(ResponseHandler handler,int maxHeaderBytes)
    {
        this(handler,maxHeaderBytes,compliance());
    }

    /* ------------------------------------------------------------------------------- */
    public HttpParser(RequestHandler handler,HttpCompliance compliance)
    {
        this(handler,-1,compliance);
    }

    /* ------------------------------------------------------------------------------- */
    public HttpParser(RequestHandler handler,int maxHeaderBytes,HttpCompliance compliance)
    {
        _handler=handler;
        _requestHandler=handler;
        _responseHandler=null;
        _maxHeaderBytes=maxHeaderBytes;
        _compliance=compliance==null?compliance():compliance;
        _complianceHandler=(ComplianceHandler)(handler instanceof ComplianceHandler?handler:null);
    }

    /* ------------------------------------------------------------------------------- */
    public HttpParser(ResponseHandler handler,int maxHeaderBytes,HttpCompliance compliance)
    {
        _handler=handler;
        _requestHandler=null;
        _responseHandler=handler;
        _maxHeaderBytes=maxHeaderBytes;
        _compliance=compliance==null?compliance():compliance;
        _complianceHandler=(ComplianceHandler)(handler instanceof ComplianceHandler?handler:null);
    }

    /* ------------------------------------------------------------------------------- */
    public HttpHandler getHandler()
    {
        return _handler;
    }
    
    /* ------------------------------------------------------------------------------- */
    /** Check RFC compliance violation
     * @param compliance The compliance level violated
     * @param reason The reason for the violation
     * @return True if the current compliance level is set so as to Not allow this violation
     */
    protected boolean complianceViolation(HttpCompliance compliance,String reason)
    {
        if (_complianceHandler==null)
            return _compliance.ordinal()>=compliance.ordinal();
        if (_compliance.ordinal()<compliance.ordinal())
        {
            _complianceHandler.onComplianceViolation(_compliance,compliance,reason);
            return false;
        }
        return true;
    }

    /* ------------------------------------------------------------------------------- */
    protected String caseInsensitiveHeader(String orig, String normative)
    {                   
        return (_compliance!=LEGACY || orig.equals(normative) || complianceViolation(RFC2616,"https://tools.ietf.org/html/rfc2616#section-4.2 case sensitive header: "+orig))
                ?normative:orig;
    }
    
    /* ------------------------------------------------------------------------------- */
    public long getContentLength()
    {
        return _contentLength;
    }

    /* ------------------------------------------------------------ */
    public long getContentRead()
    {
        return _contentPosition;
    }

    /* ------------------------------------------------------------ */
    /** Set if a HEAD response is expected
     * @param head true if head response is expected
     */
    public void setHeadResponse(boolean head)
    {
        _headResponse=head;
    }

    /* ------------------------------------------------------------------------------- */
    protected void setResponseStatus(int status)
    {
        _responseStatus=status;
    }

    /* ------------------------------------------------------------------------------- */
    public State getState()
    {
        return _state;
    }

    /* ------------------------------------------------------------------------------- */
    public boolean inContentState()
    {
        return _state.ordinal()>=State.CONTENT.ordinal() && _state.ordinal()<State.END.ordinal();
    }

    /* ------------------------------------------------------------------------------- */
    public boolean inHeaderState()
    {
        return _state.ordinal() < State.CONTENT.ordinal();
    }

    /* ------------------------------------------------------------------------------- */
    public boolean isChunking()
    {
        return _endOfContent==EndOfContent.CHUNKED_CONTENT;
    }

    /* ------------------------------------------------------------ */
    public boolean isStart()
    {
        return isState(State.START);
    }

    /* ------------------------------------------------------------ */
    public boolean isClose()
    {
        return isState(State.CLOSE);
    }

    /* ------------------------------------------------------------ */
    public boolean isClosed()
    {
        return isState(State.CLOSED);
    }

    /* ------------------------------------------------------------ */
    public boolean isIdle()
    {
        return __idleStates.contains(_state);
    }

    /* ------------------------------------------------------------ */
    public boolean isComplete()
    {
        return __completeStates.contains(_state);
    }

    /* ------------------------------------------------------------------------------- */
    public boolean isState(State state)
    {
        return _state == state;
    }

    /* ------------------------------------------------------------------------------- */
    enum CharState { ILLEGAL, CR, LF, LEGAL }
    private final static CharState[] __charState;
    static
    {
        // token          = 1*tchar
        // tchar          = "!" / "#" / "$" / "%" / "&" / "'" / "*"
        //                / "+" / "-" / "." / "^" / "_" / "`" / "|" / "~"
        //                / DIGIT / ALPHA
        //                ; any VCHAR, except delimiters
        // quoted-string  = DQUOTE *( qdtext / quoted-pair ) DQUOTE
        // qdtext         = HTAB / SP /%x21 / %x23-5B / %x5D-7E / obs-text
        // obs-text       = %x80-FF
        // comment        = "(" *( ctext / quoted-pair / comment ) ")"
        // ctext          = HTAB / SP / %x21-27 / %x2A-5B / %x5D-7E / obs-text
        // quoted-pair    = "\" ( HTAB / SP / VCHAR / obs-text )

        __charState=new CharState[256];
        Arrays.fill(__charState,CharState.ILLEGAL);
        __charState[LINE_FEED]=CharState.LF;
        __charState[CARRIAGE_RETURN]=CharState.CR;
        __charState[TAB]=CharState.LEGAL;
        __charState[SPACE]=CharState.LEGAL;

        __charState['!']=CharState.LEGAL;
        __charState['#']=CharState.LEGAL;
        __charState['$']=CharState.LEGAL;
        __charState['%']=CharState.LEGAL;
        __charState['&']=CharState.LEGAL;
        __charState['\'']=CharState.LEGAL;
        __charState['*']=CharState.LEGAL;
        __charState['+']=CharState.LEGAL;
        __charState['-']=CharState.LEGAL;
        __charState['.']=CharState.LEGAL;
        __charState['^']=CharState.LEGAL;
        __charState['_']=CharState.LEGAL;
        __charState['`']=CharState.LEGAL;
        __charState['|']=CharState.LEGAL;
        __charState['~']=CharState.LEGAL;

        __charState['"']=CharState.LEGAL;

        __charState['\\']=CharState.LEGAL;
        __charState['(']=CharState.LEGAL;
        __charState[')']=CharState.LEGAL;
        Arrays.fill(__charState,0x21,0x27+1,CharState.LEGAL);
        Arrays.fill(__charState,0x2A,0x5B+1,CharState.LEGAL);
        Arrays.fill(__charState,0x5D,0x7E+1,CharState.LEGAL);
        Arrays.fill(__charState,0x80,0xFF+1,CharState.LEGAL);

    }

    /* ------------------------------------------------------------------------------- */
    private byte next(ByteBuffer buffer)
    {
        byte ch = buffer.get();

        CharState s = __charState[0xff & ch];
        switch(s)
        {
            case ILLEGAL:
                throw new IllegalCharacterException(_state,ch,buffer);

            case LF:
                _cr=false;
                break;

            case CR:
                if (_cr)
                    throw new BadMessageException("Bad EOL");

                _cr=true;
                if (buffer.hasRemaining())
                {
                    // Don't count the CRs and LFs of the chunked encoding.
                    if (_maxHeaderBytes>0 && (_state == State.HEADER || _state == State.TRAILER))
                        _headerBytes++;
                    return next(buffer);
                }

                // Can return 0 here to indicate the need for more characters,
                // because a real 0 in the buffer would cause a BadMessage below
                return 0;

            case LEGAL:
                if (_cr)
                    throw new BadMessageException("Bad EOL");
        }

        return ch;
    }

    /* ------------------------------------------------------------------------------- */
    /* Quick lookahead for the start state looking for a request method or a HTTP version,
     * otherwise skip white space until something else to parse.
     */
    private boolean quickStart(ByteBuffer buffer)
    {
        if (_requestHandler!=null)
        {
            _method = HttpMethod.lookAheadGet(buffer);
            if (_method!=null)
            {
                _methodString = _method.asString();
                buffer.position(buffer.position()+_methodString.length()+1);

                setState(State.SPACE1);
                return false;
            }
        }
        else if (_responseHandler!=null)
        {
            _version = HttpVersion.lookAheadGet(buffer);
            if (_version!=null)
            {
                buffer.position(buffer.position()+_version.asString().length()+1);
                setState(State.SPACE1);
                return false;
            }
        }

        // Quick start look
        while (_state==State.START && buffer.hasRemaining())
        {
            int ch=next(buffer);

            if (ch > SPACE)
            {
                _string.setLength(0);
                _string.append((char)ch);
                setState(_requestHandler!=null?State.METHOD:State.RESPONSE_VERSION);
                return false;
            }
            else if (ch==0)
                break;
            else if (ch<0)
                throw new BadMessageException();

            // count this white space as a header byte to avoid DOS
            if (_maxHeaderBytes>0 && ++_headerBytes>_maxHeaderBytes)
            {
                LOG.warn("padding is too large >"+_maxHeaderBytes);
                throw new BadMessageException(HttpStatus.BAD_REQUEST_400);
            }
        }
        return false;
    }

    /* ------------------------------------------------------------------------------- */
    private void setString(String s)
    {
        _string.setLength(0);
        _string.append(s);
        _length=s.length();
    }

    /* ------------------------------------------------------------------------------- */
    private String takeString()
    {
        _string.setLength(_length);
        String s =_string.toString();
        _string.setLength(0);
        _length=-1;
        return s;
    }
    
    /* ------------------------------------------------------------------------------- */
    private boolean handleHeaderContentMessage()
    {
        boolean handle_header = _handler.headerComplete();
        _headerComplete = true;
        boolean handle_content = _handler.contentComplete();
        boolean handle_message = _handler.messageComplete();
        return handle_header || handle_content || handle_message;
    }
    
    /* ------------------------------------------------------------------------------- */
    private boolean handleContentMessage()
    {
        boolean handle_content = _handler.contentComplete();
        boolean handle_message = _handler.messageComplete();
        return handle_content || handle_message;
    }

    /* ------------------------------------------------------------------------------- */
    /* Parse a request or response line
     */
    private boolean parseLine(ByteBuffer buffer)
    {
        boolean handle=false;

        // Process headers
        while (_state.ordinal()<State.HEADER.ordinal() && buffer.hasRemaining() && !handle)
        {
            // process each character
            byte b=next(buffer);
            if (b==0)
                break;

            if (_maxHeaderBytes>0 && ++_headerBytes>_maxHeaderBytes)
            {
                if (_state==State.URI)
                {
                    LOG.warn("URI is too large >"+_maxHeaderBytes);
                    throw new BadMessageException(HttpStatus.URI_TOO_LONG_414);
                }
                else
                {
                    if (_requestHandler!=null)
                        LOG.warn("request is too large >"+_maxHeaderBytes);
                    else
                        LOG.warn("response is too large >"+_maxHeaderBytes);
                    throw new BadMessageException(HttpStatus.REQUEST_HEADER_FIELDS_TOO_LARGE_431);
                }
            }

            switch (_state)
            {
                case METHOD:
                    if (b == SPACE)
                    {
                        _length=_string.length();
                        _methodString=takeString();

                        // TODO #1966 This cache lookup is case insensitive when it should be case sensitive by RFC2616, RFC7230
                        HttpMethod method=HttpMethod.CACHE.get(_methodString);
                        if (method!=null)
                        {
                            switch(_compliance)
                            {
                                case LEGACY:
                                    // Legacy correctly allows case sensitive header;
                                    break;

                                case RFC2616:
                                case RFC7230:
                                    if (!method.asString().equals(_methodString) && _complianceHandler!=null)
                                        _complianceHandler.onComplianceViolation(_compliance,HttpCompliance.LEGACY,
                                                "https://tools.ietf.org/html/rfc7230#section-3.1.1 case insensitive method "+_methodString);
                                    // TODO Good to used cached version for faster equals checking, but breaks case sensitivity because cache is insensitive
                                    _methodString = method.asString();  
                                    break;
                            }                       
                        }
                        setState(State.SPACE1);
                    }
                    else if (b < SPACE)
                    {
                        if (b==LINE_FEED)
                            throw new BadMessageException("No URI");
                        else
                            throw new IllegalCharacterException(_state,b,buffer);
                    }
                    else
                        _string.append((char)b);
                    break;

                case RESPONSE_VERSION:
                    if (b == HttpTokens.SPACE)
                    {
                        _length=_string.length();
                        String version=takeString();
                        _version=HttpVersion.CACHE.get(version);
                        if (_version==null)
                            throw new BadMessageException(HttpStatus.BAD_REQUEST_400,"Unknown Version");
                        setState(State.SPACE1);
                    }
                    else if (b < HttpTokens.SPACE)
                        throw new IllegalCharacterException(_state,b,buffer);
                    else
                        _string.append((char)b);
                    break;

                case SPACE1:
                    if (b > HttpTokens.SPACE || b<0)
                    {
                        if (_responseHandler!=null)
                        {
                            setState(State.STATUS);
                            setResponseStatus(b-'0');
                        }
                        else
                        {
                            _uri.reset();
                            setState(State.URI);
                            // quick scan for space or EoBuffer
                            if (buffer.hasArray())
                            {
                                byte[] array=buffer.array();
                                int p=buffer.arrayOffset()+buffer.position();
                                int l=buffer.arrayOffset()+buffer.limit();
                                int i=p;
                                while (i<l && array[i]>HttpTokens.SPACE)
                                    i++;

                                int len=i-p;
                                _headerBytes+=len;

                                if (_maxHeaderBytes>0 && ++_headerBytes>_maxHeaderBytes)
                                {
                                    LOG.warn("URI is too large >"+_maxHeaderBytes);
                                    throw new BadMessageException(HttpStatus.URI_TOO_LONG_414);
                                }
                                _uri.append(array,p-1,len+1);
                                buffer.position(i-buffer.arrayOffset());
                            }
                            else
                                _uri.append(b);
                        }
                    }
                    else if (b < HttpTokens.SPACE)
                    {
                        throw new BadMessageException(HttpStatus.BAD_REQUEST_400,_requestHandler!=null?"No URI":"No Status");
                    }
                    break;

                case STATUS:
                    if (b == HttpTokens.SPACE)
                    {
                        setState(State.SPACE2);
                    }
                    else if (b>='0' && b<='9')
                    {
                        _responseStatus=_responseStatus*10+(b-'0');
                    }
                    else if (b < HttpTokens.SPACE && b>=0)
                    {
                        setState(State.HEADER);
                        handle=_responseHandler.startResponse(_version, _responseStatus, null)||handle;
                    }
                    else
                    {
                        throw new BadMessageException();
                    }
                    break;

                case URI:
                    if (b == HttpTokens.SPACE)
                    {
                        setState(State.SPACE2);
                    }
                    else if (b < HttpTokens.SPACE && b>=0)
                    {
                        // HTTP/0.9
                        if (complianceViolation(RFC7230,"https://tools.ietf.org/html/rfc7230#appendix-A.2 HTTP/0.9"))
                            throw new BadMessageException("HTTP/0.9 not supported");
                        handle=_requestHandler.startRequest(_methodString,_uri.toString(), HttpVersion.HTTP_0_9);
                        setState(State.END);
                        BufferUtil.clear(buffer);
                        handle= handleHeaderContentMessage() || handle;
                    }
                    else
                    {
                        _uri.append(b);
                    }
                    break;

                case SPACE2:
                    if (b > HttpTokens.SPACE)
                    {
                        _string.setLength(0);
                        _string.append((char)b);
                        if (_responseHandler!=null)
                        {
                            _length=1;
                            setState(State.REASON);
                        }
                        else
                        {
                            setState(State.REQUEST_VERSION);

                            // try quick look ahead for HTTP Version
                            HttpVersion version;
                            if (buffer.position()>0 && buffer.hasArray())
                                version=HttpVersion.lookAheadGet(buffer.array(),buffer.arrayOffset()+buffer.position()-1,buffer.arrayOffset()+buffer.limit());
                            else
                                version=HttpVersion.CACHE.getBest(buffer,0,buffer.remaining());

                            if (version!=null)
                            {
                                int pos = buffer.position()+version.asString().length()-1;
                                if (pos<buffer.limit())
                                {
                                    byte n=buffer.get(pos);
                                    if (n==HttpTokens.CARRIAGE_RETURN)
                                    {
                                        _cr=true;
                                        _version=version;
                                        _string.setLength(0);
                                        buffer.position(pos+1);
                                    }
                                    else if (n==HttpTokens.LINE_FEED)
                                    {
                                        _version=version;
                                        _string.setLength(0);
                                        buffer.position(pos);
                                    }
                                }
                            }
                        }
                    }
                    else if (b == HttpTokens.LINE_FEED)
                    {
                        if (_responseHandler!=null)
                        {
                            setState(State.HEADER);
                            handle=_responseHandler.startResponse(_version, _responseStatus, null)||handle;
                        }
                        else
                        {
                            // HTTP/0.9
                            if (complianceViolation(RFC7230,"https://tools.ietf.org/html/rfc7230#appendix-A.2 HTTP/0.9"))
                                throw new BadMessageException("HTTP/0.9 not supported");

                            handle=_requestHandler.startRequest(_methodString,_uri.toString(), HttpVersion.HTTP_0_9);
                            setState(State.END);
                            BufferUtil.clear(buffer);
                            handle= handleHeaderContentMessage() || handle;
                        }
                    }
                    else if (b<0)
                        throw new BadMessageException();
                    break;

                case REQUEST_VERSION:
                    if (b == HttpTokens.LINE_FEED)
                    {
                        if (_version==null)
                        {
                            _length=_string.length();
                            _version=HttpVersion.CACHE.get(takeString());
                        }
                        if (_version==null)
                            throw new BadMessageException(HttpStatus.BAD_REQUEST_400,"Unknown Version");

                        // Should we try to cache header fields?
                        if (_fieldCache==null && _version.getVersion()>=HttpVersion.HTTP_1_1.getVersion() && _handler.getHeaderCacheSize()>0)
                        {
                            int header_cache = _handler.getHeaderCacheSize();
                            _fieldCache=new ArrayTernaryTrie<>(header_cache);
                        }

                        setState(State.HEADER);

                        handle=_requestHandler.startRequest(_methodString,_uri.toString(), _version)||handle;
                        continue;
                    }
                    else if (b>=HttpTokens.SPACE)
                        _string.append((char)b);
                    else
                        throw new BadMessageException();

                    break;

                case REASON:
                    if (b == HttpTokens.LINE_FEED)
                    {
                        String reason=takeString();
                        setState(State.HEADER);
                        handle=_responseHandler.startResponse(_version, _responseStatus, reason)||handle;
                        continue;
                    }
                    else if (b>=HttpTokens.SPACE || ((b<0) && (b>=-96)))
                    {
                        _string.append((char)(0xff&b));
                        if (b!=' '&&b!='\t')
                            _length=_string.length();
                    }
                    else
                        throw new BadMessageException();
                    break;

                default:
                    throw new IllegalStateException(_state.toString());
            }
        }

        return handle;
    }

    private void parsedHeader()
    {
        // handler last header if any.  Delayed to here just in case there was a continuation line (above)
        if (_headerString!=null || _valueString!=null)
        {
            // Handle known headers
            if (_header!=null)
            {
                boolean add_to_connection_trie=false;
                switch (_header)
                {
                    case CONTENT_LENGTH:
                        if (_endOfContent == EndOfContent.CONTENT_LENGTH)
                        {
                            throw new BadMessageException(HttpStatus.BAD_REQUEST_400, "Duplicate Content-Length");
                        }
                        else if (_endOfContent != EndOfContent.CHUNKED_CONTENT)
                        {
                            _contentLength=convertContentLength(_valueString);
                            if (_contentLength <= 0)
                                _endOfContent=EndOfContent.NO_CONTENT;
                            else
                                _endOfContent=EndOfContent.CONTENT_LENGTH;
                        }
                        break;

                    case TRANSFER_ENCODING:
                        if (HttpHeaderValue.CHUNKED.is(_valueString))
                        {
                            _endOfContent=EndOfContent.CHUNKED_CONTENT;
                            _contentLength=-1;
                        }
                        else
                        {
                            List<String> values = new QuotedCSV(_valueString).getValues();
                            if (values.size()>0 && HttpHeaderValue.CHUNKED.is(values.get(values.size()-1)))
                            {
                                _endOfContent=EndOfContent.CHUNKED_CONTENT;
                                _contentLength=-1;
                            }
                            else if (values.stream().anyMatch(HttpHeaderValue.CHUNKED::is))
                                throw new BadMessageException(HttpStatus.BAD_REQUEST_400,"Bad chunking");
                        }
                        break;

                    case HOST:
                        _host=true;
                        if (!(_field instanceof HostPortHttpField) && _valueString!=null && !_valueString.isEmpty())
                        {
                            _field=new HostPortHttpField(_header,caseInsensitiveHeader(_headerString,_header.asString()),_valueString);
                            add_to_connection_trie=_fieldCache!=null;
                        }
                      break;

                    case CONNECTION:
                        // Don't cache headers if not persistent
                        if (HttpHeaderValue.CLOSE.is(_valueString) || new QuotedCSV(_valueString).getValues().stream().anyMatch(HttpHeaderValue.CLOSE::is))
                            _fieldCache=null;
                        break;

                    case AUTHORIZATION:
                    case ACCEPT:
                    case ACCEPT_CHARSET:
                    case ACCEPT_ENCODING:
                    case ACCEPT_LANGUAGE:
                    case COOKIE:
                    case CACHE_CONTROL:
                    case USER_AGENT:
                        add_to_connection_trie=_fieldCache!=null && _field==null;
                        break;

                    default: break;

                }

                if (add_to_connection_trie && !_fieldCache.isFull() && _header!=null && _valueString!=null)
                {
                    if (_field==null)
                        _field=new HttpField(_header,caseInsensitiveHeader(_headerString,_header.asString()),_valueString);
                    _fieldCache.put(_field);
                }
            }
            _handler.parsedHeader(_field!=null?_field:new HttpField(_header,_headerString,_valueString));
        }

        _headerString=_valueString=null;
        _header=null;
        _field=null;
    }

    private void parsedTrailer()
    {
        // handler last header if any.  Delayed to here just in case there was a continuation line (above)
        if (_headerString!=null || _valueString!=null)
            _handler.parsedTrailer(_field!=null?_field:new HttpField(_header,_headerString,_valueString));

        _headerString=_valueString=null;
        _header=null;
        _field=null;
    }
    
    private long convertContentLength(String valueString)
    {
        try
        {
            return Long.parseLong(valueString);
        }
        catch(NumberFormatException e)
        {
            LOG.ignore(e);
            throw new BadMessageException(HttpStatus.BAD_REQUEST_400,"Invalid Content-Length Value");
        }
    }

    /* ------------------------------------------------------------------------------- */
    /*
     * Parse the message headers and return true if the handler has signaled for a return
     */
    protected boolean parseFields(ByteBuffer buffer)
    {
        // Process headers
        while ((_state==State.HEADER || _state==State.TRAILER) && buffer.hasRemaining())
        {
            // process each character
            byte b=next(buffer);
            if (b==0)
                break;

            if (_maxHeaderBytes>0 && ++_headerBytes>_maxHeaderBytes)
            {
                boolean header = _state == State.HEADER;
                LOG.warn("{} is too large {}>{}", header ? "Header" : "Trailer", _headerBytes, _maxHeaderBytes);
                throw new BadMessageException(header ?
                        HttpStatus.REQUEST_HEADER_FIELDS_TOO_LARGE_431 :
                        HttpStatus.PAYLOAD_TOO_LARGE_413);
            }

            switch (_fieldState)
            {
                case FIELD:
                    switch(b)
                    {
                        case HttpTokens.COLON:
                        case HttpTokens.SPACE:
                        case HttpTokens.TAB:
                        {
                            if (complianceViolation(RFC7230,"https://tools.ietf.org/html/rfc7230#section-3.2.4 folding"))
                                throw new BadMessageException(HttpStatus.BAD_REQUEST_400,"Header Folding");

                            // header value without name - continuation?
                            if (_valueString==null)
                            {
                                _string.setLength(0);
                                _length=0;
                            }
                            else
                            {
                                setString(_valueString);
                                _string.append(' ');
                                _length++;
                                _valueString=null;
                            }
                            setState(FieldState.VALUE);
                            break;
                        }

                        case HttpTokens.LINE_FEED:
                        {
                            // process previous header
                            if (_state==State.HEADER)
                                parsedHeader();
                            else
                                parsedTrailer();

                            _contentPosition=0;

                            // End of headers or trailers?
                            if (_state==State.TRAILER)
                            {
                                setState(State.END);
                                return _handler.messageComplete();
                            }
                            
                            // Was there a required host header?
                            if (!_host && _version==HttpVersion.HTTP_1_1 && _requestHandler!=null)
                            {
                                throw new BadMessageException(HttpStatus.BAD_REQUEST_400,"No Host");
                            }

                            // is it a response that cannot have a body?
                            if (_responseHandler !=null  && // response
                                    (_responseStatus == 304  || // not-modified response
                                    _responseStatus == 204 || // no-content response
                                    _responseStatus < 200)) // 1xx response
                                _endOfContent=EndOfContent.NO_CONTENT; // ignore any other headers set

                            // else if we don't know framing
                            else if (_endOfContent == EndOfContent.UNKNOWN_CONTENT)
                            {
                                if (_responseStatus == 0  // request
                                        || _responseStatus == 304 // not-modified response
                                        || _responseStatus == 204 // no-content response
                                        || _responseStatus < 200) // 1xx response
                                    _endOfContent=EndOfContent.NO_CONTENT;
                                else
                                    _endOfContent=EndOfContent.EOF_CONTENT;
                            }

                            // How is the message ended?
                            switch (_endOfContent)
                            {
                                case EOF_CONTENT:
                                {
                                    setState(State.EOF_CONTENT);
                                    boolean handle=_handler.headerComplete();
                                    _headerComplete=true;
                                    return handle;
                                }
                                case CHUNKED_CONTENT:
                                {
                                    setState(State.CHUNKED_CONTENT);
                                    boolean handle=_handler.headerComplete();
                                    _headerComplete=true;
                                    return handle;
                                }
                                case NO_CONTENT:
                                {
                                    setState(State.END);
                                    return handleHeaderContentMessage();
                                }
                                default:
                                {
                                    setState(State.CONTENT);
                                    boolean handle=_handler.headerComplete();
                                    _headerComplete=true;
                                    return handle;
                                }
                            }
                        }

                        default:
                        {
                            // now handle the ch
                            if (b<HttpTokens.SPACE)
                                throw new BadMessageException();

                            // process previous header
                            if (_state==State.HEADER)
                                parsedHeader();
                            else
                                parsedTrailer();

                            // handle new header
                            if (buffer.hasRemaining())
                            {
                                // Try a look ahead for the known header name and value.
                                HttpField field=_fieldCache==null?null:_fieldCache.getBest(buffer,-1,buffer.remaining());
                                if (field==null)
                                    field=CACHE.getBest(buffer,-1,buffer.remaining());

                                if (field!=null)
                                {
                                    final String n;
                                    final String v;

                                    if (_compliance==LEGACY)
                                    {
                                        // Have to get the fields exactly from the buffer to match case
                                        String fn=field.getName();
                                        n=caseInsensitiveHeader(BufferUtil.toString(buffer,buffer.position()-1,fn.length(),StandardCharsets.US_ASCII),fn);
                                        String fv=field.getValue();
                                        if (fv==null)
                                            v=null;
                                        else
                                        {
                                            v=caseInsensitiveHeader(BufferUtil.toString(buffer,buffer.position()+fn.length()+1,fv.length(),StandardCharsets.ISO_8859_1),fv);
                                            field=new HttpField(field.getHeader(),n,v);
                                        }
                                    }
                                    else
                                    {
                                        n=field.getName();
                                        v=field.getValue();
                                    }

                                    _header=field.getHeader();
                                    _headerString=n;

                                    if (v==null)
                                    {
                                        // Header only
                                        setState(FieldState.VALUE);
                                        _string.setLength(0);
                                        _length=0;
                                        buffer.position(buffer.position()+n.length()+1);
                                        break;
                                    }
                                    else
                                    {
                                        // Header and value
                                        int pos=buffer.position()+n.length()+v.length()+1;
                                        byte peek=buffer.get(pos);

                                        if (peek==HttpTokens.CARRIAGE_RETURN || peek==HttpTokens.LINE_FEED)
                                        {
                                            _field=field;
                                            _valueString=v;
                                            setState(FieldState.IN_VALUE);

                                            if (peek==HttpTokens.CARRIAGE_RETURN)
                                            {
                                                _cr=true;
                                                buffer.position(pos+1);
                                            }
                                            else
                                                buffer.position(pos);
                                            break;
                                        }
                                        else
                                        {
                                            setState(FieldState.IN_VALUE);
                                            setString(v);
                                            buffer.position(pos);
                                            break;
                                        }
                                    }
                                }
                            }

                            // New header
                            setState(FieldState.IN_NAME);
                            _string.setLength(0);
                            _string.append((char)b);
                            _length=1;

                        }
                    }
                    break;

                case IN_NAME:
                    if (b==HttpTokens.COLON)
                    {
                        if (_headerString==null)
                        {
                            _headerString=takeString();
                            _header=HttpHeader.CACHE.get(_headerString);
                        }
                        _length=-1;

                        setState(FieldState.VALUE);
                        break;
                    }

                    if (b>HttpTokens.SPACE)
                    {
                        if (_header!=null)
                        {
                            setString(_header.asString());
                            _header=null;
                            _headerString=null;
                        }

                        _string.append((char)b);
                        if (b>HttpTokens.SPACE)
                            _length=_string.length();
                        break;
                    }
                    
                    if (b==HttpTokens.LINE_FEED && !complianceViolation(RFC7230,"https://tools.ietf.org/html/rfc7230#section-3.2 No colon"))
                    {
                        if (_headerString==null)
                        {
                            _headerString=takeString();
                            _header=HttpHeader.CACHE.get(_headerString);
                        }
                        _string.setLength(0);
                        _valueString="";
                        _length=-1;

                        setState(FieldState.FIELD);
                        break;
                    }

                    throw new IllegalCharacterException(_state,b,buffer);

                case VALUE:
                    if (b>HttpTokens.SPACE || b<0)
                    {
                        _string.append((char)(0xff&b));
                        _length=_string.length();
                        setState(FieldState.IN_VALUE);
                        break;
                    }

                    if (b==HttpTokens.SPACE || b==HttpTokens.TAB)
                        break;

                    if (b==HttpTokens.LINE_FEED)
                    {
                        _string.setLength(0);
                        _valueString="";
                        _length=-1;

                        setState(FieldState.FIELD);
                        break;
                    }
                    throw new IllegalCharacterException(_state,b,buffer);

                case IN_VALUE:
                    if (b>=HttpTokens.SPACE || b<0 || b==HttpTokens.TAB)
                    {
                        if (_valueString!=null)
                        {
                            setString(_valueString);
                            _valueString=null;
                            _field=null;
                        }
                        _string.append((char)(0xff&b));
                        if (b>HttpTokens.SPACE || b<0)
                            _length=_string.length();
                        break;
                    }

                    if (b==HttpTokens.LINE_FEED)
                    {
                        if (_length > 0)
                        {
                            _valueString=takeString();
                            _length=-1;
                        }
                        setState(FieldState.FIELD);
                        break;
                    }

                    throw new IllegalCharacterException(_state,b,buffer);

                default:
                    throw new IllegalStateException(_state.toString());

            }
        }

        return false;
    }

    /* ------------------------------------------------------------------------------- */
    /**
     * Parse until next Event.
     * @param buffer the buffer to parse
     * @return True if an {@link RequestHandler} method was called and it returned true;
     */
    public boolean parseNext(ByteBuffer buffer)
    {
        if (DEBUG)
            LOG.debug("parseNext s={} {}",_state,BufferUtil.toDetailString(buffer));
        try
        {
            // Start a request/response
            if (_state==State.START)
            {
                _version=null;
                _method=null;
                _methodString=null;
                _endOfContent=EndOfContent.UNKNOWN_CONTENT;
                _header=null;
                if (quickStart(buffer))
                    return true;
            }

            // Request/response line
            if (_state.ordinal()>= State.START.ordinal() && _state.ordinal()<State.HEADER.ordinal())
            {
                if (parseLine(buffer))
                    return true;
            }

            // parse headers
            if (_state== State.HEADER)
            {
                if (parseFields(buffer))
                    return true;
            }

            // parse content
            if (_state.ordinal()>= State.CONTENT.ordinal() && _state.ordinal()<State.TRAILER.ordinal())
            {
                // Handle HEAD response
                if (_responseStatus>0 && _headResponse)
                {
                    setState(State.END);
                    return handleContentMessage();
                }
                else
                {
                    if (parseContent(buffer))
                        return true;
                }
            }

            // parse headers
            if (_state==State.TRAILER)
            {
                if (parseFields(buffer))
                    return true;
            }

            // handle end states
            if (_state==State.END)
            {
                // eat white space
                while (buffer.remaining()>0 && buffer.get(buffer.position())<=HttpTokens.SPACE)
                    buffer.get();
            }
            else if (isClose() || isClosed())
            {
                BufferUtil.clear(buffer);
            }

            // Handle EOF
            if (_eof && !buffer.hasRemaining())
            {
                switch(_state)
                {
                    case CLOSED:
                        break;

                    case START:
                        setState(State.CLOSED);
                        _handler.earlyEOF();
                        break;

                    case END:
                    case CLOSE:
                        setState(State.CLOSED);
                        break;

                    case EOF_CONTENT:
                    case TRAILER:
                        if (_fieldState==FieldState.FIELD)
                        {
                            // Be forgiving of missing last CRLF
                            setState(State.CLOSED);
                            return handleContentMessage();
                        }
                        setState(State.CLOSED);
                        _handler.earlyEOF();
                        break;
                        
                    case CONTENT:
                    case CHUNKED_CONTENT:
                    case CHUNK_SIZE:
                    case CHUNK_PARAMS:
                    case CHUNK:
                        setState(State.CLOSED);
                        _handler.earlyEOF();
                        break;

                    default:
                        if (DEBUG)
                            LOG.debug("{} EOF in {}",this,_state);
                        setState(State.CLOSED);
                        _handler.badMessage(HttpStatus.BAD_REQUEST_400,null);
                        break;
                }
            }
        }
        catch(BadMessageException x)
        {
            BufferUtil.clear(buffer);
            badMessage(x);
        }
        catch(Throwable x)
        {
            BufferUtil.clear(buffer);
            badMessage(new BadMessageException(HttpStatus.BAD_REQUEST_400, _requestHandler != null ? "Bad Request" : "Bad Response", x));
        }
        return false;
    }
    
    protected void badMessage(BadMessageException x)
    {
        if (DEBUG)
            LOG.debug("Parse exception: " + this + " for " + _handler, x);
        setState(State.CLOSE);
        if (_headerComplete)
            _handler.earlyEOF();
        else
            _handler.badMessage(x._code, x._reason);
    }

    protected boolean parseContent(ByteBuffer buffer)
    {
        int remaining=buffer.remaining();
        if (remaining==0 && _state==State.CONTENT)
        {
            long content=_contentLength - _contentPosition;
            if (content == 0)
            {
                setState(State.END);
                return handleContentMessage();
            }
        }

        // Handle _content
        byte ch;
        while (_state.ordinal() < State.TRAILER.ordinal() && remaining>0)
        {
            switch (_state)
            {
                case EOF_CONTENT:
                    _contentChunk=buffer.asReadOnlyBuffer();
                    _contentPosition += remaining;
                    buffer.position(buffer.position()+remaining);
                    if (_handler.content(_contentChunk))
                        return true;
                    break;

                case CONTENT:
                {
                    long content=_contentLength - _contentPosition;
                    if (content == 0)
                    {
                        setState(State.END);
                        return handleContentMessage();
                    }
                    else
                    {
                        _contentChunk=buffer.asReadOnlyBuffer();

                        // limit content by expected size
                        if (remaining > content)
                        {
                            // We can cast remaining to an int as we know that it is smaller than
                            // or equal to length which is already an int.
                            _contentChunk.limit(_contentChunk.position()+(int)content);
                        }

                        _contentPosition += _contentChunk.remaining();
                        buffer.position(buffer.position()+_contentChunk.remaining());

                        if (_handler.content(_contentChunk))
                            return true;

                        if(_contentPosition == _contentLength)
                        {
                            setState(State.END);
                            return handleContentMessage();
                        }
                    }
                    break;
                }

                case CHUNKED_CONTENT:
                {
                    ch=next(buffer);
                    if (ch>HttpTokens.SPACE)
                    {
                        _chunkLength=TypeUtil.convertHexDigit(ch);
                        _chunkPosition=0;
                        setState(State.CHUNK_SIZE);
                    }

                    break;
                }

                case CHUNK_SIZE:
                {
                    ch=next(buffer);
                    if (ch==0)
                        break;
                    if (ch == HttpTokens.LINE_FEED)
                    {
                        if (_chunkLength == 0)
                        {
                            setState(State.TRAILER);
                            if (_handler.contentComplete())
                                return true;
                        }
                        else
                            setState(State.CHUNK);
                    }
                    else if (ch <= HttpTokens.SPACE || ch == HttpTokens.SEMI_COLON)
                        setState(State.CHUNK_PARAMS);
                    else
                        _chunkLength=_chunkLength * 16 + TypeUtil.convertHexDigit(ch);
                    break;
                }

                case CHUNK_PARAMS:
                {
                    ch=next(buffer);
                    if (ch == HttpTokens.LINE_FEED)
                    {
                        if (_chunkLength == 0)
                        {
                            setState(State.TRAILER);
                            if (_handler.contentComplete())
                                return true;
                        }
                        else
                            setState(State.CHUNK);
                    }
                    break;
                }

                case CHUNK:
                {
                    int chunk=_chunkLength - _chunkPosition;
                    if (chunk == 0)
                    {
                        setState(State.CHUNKED_CONTENT);
                    }
                    else
                    {
                        _contentChunk=buffer.asReadOnlyBuffer();

                        if (remaining > chunk)
                            _contentChunk.limit(_contentChunk.position()+chunk);
                        chunk=_contentChunk.remaining();

                        _contentPosition += chunk;
                        _chunkPosition += chunk;
                        buffer.position(buffer.position()+chunk);
                        if (_handler.content(_contentChunk))
                            return true;
                    }
                    break;
                }

                case CLOSED:
                {
                    BufferUtil.clear(buffer);
                    return false;
                }

                default:
                    break;

            }

            remaining=buffer.remaining();
        }
        return false;
    }

    /* ------------------------------------------------------------------------------- */
    public boolean isAtEOF()

    {
        return _eof;
    }

    /* ------------------------------------------------------------------------------- */
    /** Signal that the associated data source is at EOF
     */
    public void atEOF()
    {
        if (DEBUG)
            LOG.debug("atEOF {}", this);
        _eof=true;
    }

    /* ------------------------------------------------------------------------------- */
    /** Request that the associated data source be closed
     */
    public void close()
    {
        if (DEBUG)
            LOG.debug("close {}", this);
        setState(State.CLOSE);
    }

    /* ------------------------------------------------------------------------------- */
    public void reset()
    {
        if (DEBUG)
            LOG.debug("reset {}", this);

        // reset state
        if (_state==State.CLOSE || _state==State.CLOSED)
            return;

        setState(State.START);
        _endOfContent=EndOfContent.UNKNOWN_CONTENT;
        _contentLength=-1;
        _contentPosition=0;
        _responseStatus=0;
        _contentChunk=null;
        _headerBytes=0;
        _host=false;
        _headerComplete=false;
    }

    /* ------------------------------------------------------------------------------- */
    protected void setState(State state)
    {
        if (DEBUG)
            LOG.debug("{} --> {}",_state,state);
        _state=state;
    }

    /* ------------------------------------------------------------------------------- */
    protected void setState(FieldState state)
    {
        if (DEBUG)
            LOG.debug("{}:{} --> {}",_state,_field,state);
        _fieldState=state;
    }

    /* ------------------------------------------------------------------------------- */
    public Trie<HttpField> getFieldCache()
    {
        return _fieldCache;
    }

    /* ------------------------------------------------------------------------------- */
    @Override
    public String toString()
    {
        return String.format("%s{s=%s,%d of %d}",
                getClass().getSimpleName(),
                _state,
                _contentPosition,
                _contentLength);
    }

    /* ------------------------------------------------------------ */
    /* ------------------------------------------------------------ */
    /* ------------------------------------------------------------ */
    /* Event Handler interface
     * These methods return true if the caller should process the events
     * so far received (eg return from parseNext and call HttpChannel.handle).
     * If multiple callbacks are called in sequence (eg
     * headerComplete then messageComplete) from the same point in the parsing
     * then it is sufficient for the caller to process the events only once.
     */
    public interface HttpHandler
    {
        public boolean content(ByteBuffer item);

        public boolean headerComplete();

        public boolean contentComplete(); 
        
        public boolean messageComplete();

        /**
         * This is the method called by parser when a HTTP Header name and value is found
         * @param field The field parsed
         */
        public void parsedHeader(HttpField field);
        
        /**
         * This is the method called by parser when a HTTP Trailer name and value is found
         * @param field The field parsed
         */
        public default void parsedTrailer(HttpField field) {}

        /* ------------------------------------------------------------ */
        /** Called to signal that an EOF was received unexpectedly
         * during the parsing of a HTTP message
         */
        public void earlyEOF();

        /* ------------------------------------------------------------ */
        /** Called to signal that a bad HTTP message has been received.
         * @param status The bad status to send
         * @param reason The textual reason for badness
         */
        public void badMessage(int status, String reason);

        /* ------------------------------------------------------------ */
        /** @return the size in bytes of the per parser header cache
         */
        public int getHeaderCacheSize();
    }

    /* ------------------------------------------------------------------------------- */
    /* ------------------------------------------------------------------------------- */
    /* ------------------------------------------------------------------------------- */
    public interface RequestHandler extends HttpHandler
    {
        /**
         * This is the method called by parser when the HTTP request line is parsed
         * @param method The method
         * @param uri The raw bytes of the URI.  These are copied into a ByteBuffer that will not be changed until this parser is reset and reused.
         * @param version the http version in use
         * @return true if handling parsing should return.
         */
        public boolean startRequest(String method, String uri, HttpVersion version);

    }

    /* ------------------------------------------------------------------------------- */
    /* ------------------------------------------------------------------------------- */
    /* ------------------------------------------------------------------------------- */
    public interface ResponseHandler extends HttpHandler
    {
        /**
         * This is the method called by parser when the HTTP request line is parsed
         * @param version the http version in use
         * @param status the response status
         * @param reason the response reason phrase
         * @return true if handling parsing should return
         */
        public boolean startResponse(HttpVersion version, int status, String reason);
    }

    /* ------------------------------------------------------------------------------- */
    /* ------------------------------------------------------------------------------- */
    /* ------------------------------------------------------------------------------- */
    public interface ComplianceHandler extends HttpHandler
    {
        public void onComplianceViolation(HttpCompliance compliance,HttpCompliance required,String reason);
    }

    /* ------------------------------------------------------------------------------- */
    @SuppressWarnings("serial")
    private static class IllegalCharacterException extends BadMessageException
    {
        private IllegalCharacterException(State state,byte ch,ByteBuffer buffer)
        {
            super(400,String.format("Illegal character 0x%X",ch));
            // Bug #460642 - don't reveal buffers to end user
            LOG.warn(String.format("Illegal character 0x%X in state=%s for buffer %s",ch,state,BufferUtil.toDetailString(buffer)));
        }
    }
}
